Numerous spool-type valve assemblies have been developed for controlling liquids and gases, and such assemblies incorporate a wide range of structural and functional features. Such assemblies have, for many years, been of substantial size. Modern technology, however, has increasingly demanded that such valve assemblies be made of extremely small size, particularly for use in control circuits. Such assemblies must also permit shifting of the valve with extremely small force without detracting from the desired response time and/or flow.
One problem associated with known valve assemblies, specifically three-way valves employing a shiftable spool or stem, has been the inability to substantially minimize the size of the shiftable valve spool and also minimize the number of sliding seal contact points to thus minimize the friction force which must be overcome to permit breakaway of the valve spool during shifting thereof. In addition, prior valves of this general type have often relied on multiple sliding seals for effecting isolation between the various ports, and while some known valves have relied on a poppet, nevertheless the poppet itself has been structurally more complex than desired or has performed in less than in optimum manner.
Accordingly, it is an object of the present invention to provide an improved poppet-type three-way valve assembly which is believed to be advantageous in comparison to prior valve assemblies of this general type with respect to manufacturing economy, size and performance.
In the improved valve assembly of this invention, a single stem is slidably supported within a bore formed in a one-piece valve body provided with three ports which communicate with the bore at axially spaced locations. The axially centermost port functions as a load port, and the valve stem has a single valve poppet mounted thereon in encircling relationship thereto, which valve poppet is axially movable between a pair of opposed valve seats formed on the valve body for controlling communication between the load port and the bore. The stem has a passageway extending axially therethrough so as to maintain a balanced pressure axially of the valve stem.
The valve assembly, as aforesaid, incorporates an improved poppet valve mounted on the stem, which poppet valve comprises a single elastomeric poppet ring molded around a radially extending rigid support flange mounted on an axially elongated support sleeve, which support sleeve has a press fit with the valve stem. The elastomeric poppet ring integrally defines poppet seal faces on opposite axial sides thereof, and the poppet ring possesses a significant quantity of elastomeric material disposed behind each of the poppet seal faces, whereby the sealing performance of the poppet relative to the opposed valve seats is believed significantly improved.
Other objects and purposes of the present invention will be apparent to persons familiar with assemblies of this general type upon reading the following specification and inspecting the accompanying drawings.